Implement Serialize and Deserialize for RangeInclusive

When originally added, this test used to contain a `#![plugin(clippy)]`.
This was removed at some point along the way, at which point this test
no longer tests anything. It prints:

    warning: unknown lint: `identity_op`
     --> src/main.rs:1:9
      |
    1 | #![deny(identity_op)]
      |         ^^^^^^^^^^^
      |
      = note: #[warn(unknown_lints)] on by default

which is swallowed and ignored by compiletest.

Nowadays Clippy handles warnings inside of macro expanded code
intelligently and this is something they would be responsible for
testing.

Provide ops::Range impls whether or not std is used

Share some code between the Range and RangeInclusive impls